A known technique used for manufacturing a printed circuit board or the like is a technique in which a conductive film formed of a metal sintered body is formed on a surface of a substrate such as a resin film by application and firing of an ink containing a metal powder.
It has been proposed that, in order to improve adhesion of such a metal sintered body to a resin film, a crystallite size of a metal powder dispersed in an ink is set to a particular value or more, and a porosity of a sintered body layer is set to 1% or less (refer to Japanese Unexamined Patent Application Publication No. 2010-192841).